1. Field of the Invention
This invention relates to signal conditioning and commutation circuitry and, more particularly, to programmable integrated signal conditioning and commutation circuitry useful for telemetry and other like systems.
2. Background of the Invention
In a great many information processing systems, and in particular telemetry systems such as are utilized for communicating between ground stations and airborne vehicles such as missiles, an important subsystem of the telemetry system is that portion which commutates, or multiplexes a plurality of data inputs into a single communication channel, as well as conditioning the signals received from the multiple data input sub-channels so that they are of requisite form and condition for transmission. In such systems, the commutating or multiplexing is suitably time commutating, wherein each one of a large multiple of data inputs is sampled for a given time interval, or channel, such that a given "frame" of the communicated signal constitutes successive sampled signal levels corresponding to each one of the respective data inputs. The multiple data inputs are derived typically from multiple sensors, operating instruments, measuring devices, and the like, and consequently are non-uniform in terms of operating characteristics such as dynamic range, offset, source impedance, frequency characteristics, etc. In order that each channel, or data input, will be uniform and be compatible with the rest of the system, i.e., interface with the remaining part of the communication system, each signal is conventionally treated or conditioned in a separate conditioning path. Such conditioning paths conventionally are comprised of a plurality of active circuits, typically comprising operational amplifiers, wherein each amplifier stage is designed to condition the signal with respect to a respective different parameter. These parameters include, e.g., gain; offset; source impedance; and bandwidth. As is understood by those of skill in the art, such a conditioning path which is designed specifically to properly condition a signal received from a given source will not be able to properly condition a signal received from a different source. Consequently, where N inputs must be conditioned, there are N conditioning paths. Where N is of the order of 100, it is seen that the large number of conditioning paths adds considerably to the complexity, unreliability, and expense of the conditioning subsystem.